foo.cc: In function ‘int main()’:
foo.cc:28:21: error: ‘a’ was not declared in this scope
   28 |                 if (a[i][k] > a[i][j])
      |                     ^
foo.cc:39:25: error: ‘a’ was not declared in this scope
   39 |                     if (a[k][j] < a[i][j])
      |                         ^